Ram air III cam in a 75 400?
 

Can a Ram Air III cam be installed in a stock 75 formula 400 without other modifications? Whole car has factory parts except I removed the AIR pump and installed Headman Headers. Is there a better choice? 2.56 rear, TH350, 7.6:1 cr before heads were done, dual 2.5 exhaust w/headers. 4bl Rochester. Smog cam has got to go! so does the 2.56 rear gears.

Not a cam expert by any means but assuming you are talking about the 744 cam, this would not be a good choice for your application. This cam requires more compression and gear. (I used 4.33's with this one) Maybe others can chime in with a better recommendation.

RAIII cam could be either 068 or 744 as both were used at one time or other in engines designated "Ram Air III". Neither is a good choice for a low compression 400 with 2.56 rear gears, though the 068 would be much better than the 744.

Comp XE256 or Summit 2800 would work well in that combo and not require any modifications to the valvetrain. With more gear you could go up one more size to the XE262, Summit 2801 or Crower 60240.

If you want more performance out of that car and want to make a change that will work good with other upgrades in the future, I'd suggest changing the rear gears. Going to even a 3.08 would make a huge difference and if you don't do a lot of freeway driving then go to a 3.42. 3.23 is also a nice choice and a good balance between freeway driveability and off-the-line performance.

OK so if I change my rear gears to 3:23, then can I install an 068 cam or is my compression still a problem? I am willing to go to 3:42 since I don't plan on taking it on the Highway. I want to keep it all Pontiac. I would like to build the engine around the 068 cam. Pro's and con's welcome

Thanks,

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The 068 cam was designed for use in high compression engines. It has a later intake closing event than modern cam designs with similar durations, thus it develops less low RPM cylinder pressure. Most aftermarket cams with durations similar to the 068 are designed for use in lower compression engines, they have a more advanced intake centerline, thus the intake valve closes sooner building more cylinder pressure which makes more torque at lower RPMs.

Why so stuck on using a Pontiac cam design? You can certainly do it, but the performance that results will not be optimum when compared to a different cam that is designed to work in a low compression engine. Changing the rear gears does not change this fact, though it will certainly make a HUGE difference to your car's performance.

I would keep the 2.56 and install the Summit 2801 or the Crower 60918, if you can find some old American made hyd lifters.

with the looooooow compression you are running I would try an XE grind.....they work very well in lower compressioned engines....ran a XE268H in my old 400 at 8 to 1 .....you might want to try a XE256, XE262 or the XE268 (this one might be a tiny bit much)

I have a friend with a Can Am who put a 744 cam in, i believe a Melling cam
it's ok
personally not the right choice for low compression
not to say it doesn't work, it does, but not efficient, especially with an Auto

I have the Lunatti version in my 400 with 13 heads
personally it can use more compression, but it's nice
fits my needs, and have a sweet choppy idle

I'd look at the Vodoo cams if i were you, but you need to make sure you have the right valve springs

if you want torque and flat tappet, there are solid cams that would work too, but probably rare to find one for a low compression motor

the edelbrock performer cam is nice, had a similar one from wolverine, great gas mileage, and ok power too. try that with 1.65 rollers and you should be all set
I think the Vodoo or XE line would give more umph now-a-days

capitalize on the torque of the motor, espcially with the gears you have.
work on the carb, intake, and distributor
there is some potential to unlock from there

hope this helps